Telephone system



Sept. 12, 1939. F. LUBBERGER 2,172,875

TELEPHONE SYSTEM Filed Nov. 15, 1937 ASTi INVENTOR. FRITZ LUBBERGERATTORNEY.

Patented Sept. 12, 1939 UNITED STATES PATENT OFFICE TELEPHONE SYSTEMFritz Lubberger, Berlin-Grunewald, Germany, as-

signor to Siemens & Halske Aktiengesellschaft, Siemensstadt, nearBerlin, Germany Application November 13, 1937, Serial No. 174,275

.' In Germany December 7, 1936 9 Claims. (Cl. 17986) A prior applicationof Benedikt Kudrna, Ser. controlled. For the purpose of increasing eili-No. 104,374, filed October 7, 1936, concerns a circiency both measurescan be employed simulcuit arrangement for selective calling by meanstaneously. of condenser-resistance arrangements which are The inventionwill be explained in detail with influenced by impulses of differentdurations at reference to the drawing but is not to be con- 5 the branchstations of party lines in remote comsidered as limited to this. Onlythose circuit demunication systems and more particularly teletails whichare necessary for understanding the phone systems, in which after thetransmission of invention and differ from the arrangements a selectiveimpulse by means of which in addition shown in the prior application arerepresented in 10 to the condensers at the wanted branchstation thedrawing. 10 also condensers at branch stations (having ring- As may beseen from the drawing a plurality ing periods of shorter duration) whichare not of branch stations AST are connected to the wanted, are broughtto a state of charge (comparty line GL leading to the central stationZSt. pletely charged or completely discharged) which The branch stationsare adapted to be called enables the associated connecting relay to beselectively from the central station 2st. The 15 controlled, thesecondensers at the stations which individual branch stations in thepresent case are not Wanted are rendered inoperative by being areselected only by means of direct current imconverted to a state ofcharge (partially or Wholly pulses of varying duration. By usingpolarized discharged or charged respectively) which no receiving relays,however, direct current impulses longer enables the associatedconnecting relays of different durations and directions can be em- 2:)

to be controlled. ployed.

According to the prior application the con- At each branch stationassociated with the densers at the stations which are not wanted arestation TSt is an impulse receiving relay J and brought into a conditionwhich no longer ena condenser-resistance arrangement 0, Wi, a

ables the associated connecting relays to be condischarge path E, anauxiliary relay B, a controlled, from the sending station. necting relayA and a source of direct current.

The present patent of addition is concerned The individual branchstations only differ from with an improvement on this arrangement andone another as regards the properties of the conconsists in that theconversion of the condensers denser resistance arrangements Wi whichdeterat the branch stations which are not wanted to mine the chargingperiod of the condenser C so a state of charge which no longer enablesthe asassociated therewith. The magnitude of the resociated connectingrelays to be controlled is sistances corresponds to the variousselecting peefiective by discharge paths disposed at each riods. Thedischarge paths, for example glow branch station. lamps, are alloperative on the attainment of the The use of discharge paths at eachbranch stasame potential by the condensers with which they tion producesthe special advantage that after are associated.

the transmission of the selective impulse no fur- When a direct currentof a particular duration ther discharge impulses need be transmittedfrom is transmitted from the central station 2st in the sending station.the known way the relays J at all the branch sta- This has the furtheradvantage that account tions energize and connect the corresponding .10

of the omission of discharge current impulses condensersC to theresistances Wi.

transmitted after the selection the selecting time It will be consideredfor example that a direct is reduced. current impulse is transmitted forselecting the The rendering inoperative of the excess charge branchstation ASTI. The duration of this imof the condensers over thedischarge paths at pulse must on the one hand be suflicient to bringeach of the branch stations which are not wanted the condenser Cl, overto resistance Wil, into a is conveniently effected in that when thediscondition enabling the connecting relay Al to be charge path becomeseiiective relays are influcontrolled but on the other hand must not beof enced which either convert the associated conas great duration as thecharging period necesdensers to a state of charge which no longer saryfor rendering the discharge path operative. to,

enables the connecting relays to be controlled or The impulse serving toselect the branch stadisconnected, or disconnect the connecting relaystion ASTI will not succeed in influencing the confor a period of timelasting until the associated necting relays in the branch stationshaving a condensers are brought to a stateof charge which longerselecting period. At the branch stations 5 no longer enables theconnecting relays to be having a shorter selecting period, for exampleASTZ, on the other hand the associated discharge path becomes operativewhen the charging period necessary for controlling the connecting relaysis over-stepped and brings about the discharge of the associatedcondensers and/or the disconnection of the connecting relays.

The switching operations in detail are as follows:

At the branch station ASTI the condenser Cl is charged over contact I7"I and resistance Wil after relay J I has operated. Since in the case inquestion the duration of the direct current impulse transmittedcorresponds to the selecting period of the branch station ASTI thecondenser CI is brought to a state of charge which enables theconnecting relay Al to be controlled, without the discharge pathdisposed in parallel to the condenser Cl becoming operative. On therelease of relay J I the condenser discharge over the contact I a I whenrestored to its normal position exerts its full efiect on the connectingrelay Al. Relay Al at contact 511! and 6a! causes the wanted subscribersstation TStl to be connected to the party line GL.

The release of the connection takes place when the subscriber at stationTStl hangs up his receiver. The restoration of the connecting relay Alcan be controlled, for example, by momentarily opening contacts (notshown) in the looking circuit of relay AI when the receiver is replacedupon the switchhook, or in any other well known manner.

At the branch station ASTIZ the excess charge on the condenser 02 mustbe rendered inoperative so that the connecting relay A2 does not operatein the present case (the impulse transmitted being longer than theselecting period of the branch station ASTZ).

This is arranged for in that on the further charging of the condenser C2over the operated contact 172 of relay J2 and resistance Wi2, thedischarge path E2 disposed in parallel with the condenser C2 becomesoperative. Consequently the relay B2 in series with the discharge pathE2 operates, short circuits the discharge path E2 at contact 8212 and atcontact 9172 disconnects the connecting relay A2. Relay B2 locks up inparallel with the condenser C2 for the rest of the duration of theselecting impulse and further until after the termination of theselecting impulse by the discharge of condenser C2. No discharge of thecondenser C2 over the connecting relay A2 can take place so long asrelay B2 is operated. The release of relay B2 can further be delayed bycopper damping.

In this way the condenser C2 is brought to a state of charge which nolonger enables the connecting relay A2 to be controlled and at the sametime the connecting relay A2 is disconnected until the state of chargenecessary for controlling the connecting relay A2 no longer obtains. Theconnecting relay A2 thus does not energize on the termination of theselecting impulseand the restoration of the contact H2 at branch stationAST2 which is not wanted, so that a false connection over contacts H112and l2a2 is prevented.

What is claimed is:

1. In a telephone system, a party line, a plurality of stations on saidline, a condenser for each station, means at each station operatedresponsive to a pulse of current received over said line for chargingsaid condensers, means at each station for connecting with said line,each of said last means operated only if its associated stationcondenser has been charged for a predetermined duration, and means ateach station effective only responsive to an overcharge of theassociated station condenser for preventing the connecting means thereatfrom being perated.

2. In a telephone system, a party line, a plurality of stations on saidline normally prevented from connecting with the line; a condenser, aconnecting relay, and a disconnecting relay associated with each of saidstations; means at each of said stations operated responsive tothetransmission of a station selecting pulse of current over said line, thepulse operated means at the wanted station controlling its associatedcondenser and connecting relay to thereby connect the station with theparty line, and the pulse operated means at all other said stationscontrolling their associated condenser and disconnect relay to therebyprevent connection of all of said other stations to said party line.

3. In a telephone system, a party line, two stations normallydisconnected from said line, a condenser and a connecting relayindividual to each of said stations, means at each station operated by astation selecting pulse transmitted over said line for charging itsassociated station condenser, the duration of charging time beingsufficient to completely charge one of said condensers and to overchargethe other of said condensers, means at each of said stations effectiveonly responsive to an overcharge of the condenser thereat fordisconnecting the associated connecting relay to prevent its operationand for discharging the overcharged condenser, and contacts controlledby said pulse operated means for completing a discharge circuit for saidcompletely charged condenser through its connecting relay to therebyoperate the same and connect the associated station to said party line.

l. In a telephone system, a line over which a pulse of current istransmitted, a station normally disconnected from said line, a firstrelay individual to said station operated responsive to said currentpulse, a condenser and a connecting relay for said station, meanscontrolled by the operation of said first relay for charging saidcondenser and for discharging the same through said connecting relaywhen said first relay restores, said connecting relay non-responsive todischarge currents of insufiicient strength and operated responsive todischarge currents of proper strength to connect the station to saidline, and means responsive only when said current pulse is more thansuflicient to completely charge said condenser for disconnecting saidconnecting relay from said discharge currents.

5. In a telephone system, a party line, a plurality of stations on saidline normally disconnected therefrom, a pulse receiving relay bridgingthe conductors of said line at each of said stations, said relaysoperated responsive to the transmission of a current pulse over saidline, a condenser and charging circuit therefor at each stationcompleted by the operation of its associated pulse receiving relay, adischarge circuit for each condenser completed responsive to therestoration of its associated pulse receiving relay, and connectingmeans at each station operated responsive to the discharge of theassociated condenser for connecting its station to said line, thestrength of the discharge current through said connecting meansdetermining the station to be connected to said party line.

6. In a telephone system, a party line, two stations on said line, meansat each station operated responsive to a pulse of current received oversaid line, a condenser and charging circuit therefor completed by theoperation of said last means, a discharge circuit for said condenser anda connecting relay included therein for connecting the station to theline, said pulse receiving means controlling the discharge circuit ofsaid condensers, a disconnect relay at each station operative to preventthe operation of its associated connecting relay, and a space dischargedevice for each station effective only responsive to an overcharge ofits associated condenser to control the operation of its associateddisconnect relay.

'7. In a system as claimed in claim 6, in which the operation of saiddisconnect relay short-circuits said space discharge device to renderitineffective.

8. In a system as claimed in claim 6, in which the operation of thedisconnect relay completes a circuit for discharging the associatedstation condenser.

9. In a system as claimed in claim 6, in which the disconnect relay uponoperation completes a locking circuit for itself including the chargingcircuit for the associated condenser.

FRITZ LUBBERGE-R.

